The invention is in the field of mechanical engineering, in particular of micromechanics, and specifically relates to fluid pumps having a rotor and at least one impeller blade for the predominantly axial conveying of a fluid.
Pumps of this kind can be used in different technical fields, particularly where deployment locations are difficult to access and a compressible rotor can be brought onto site in compressed form and can there be expanded for efficient operation.
A particularly advantageous application is in the field of medicine where pumps of this kind can be introduced in particularly small construction into the body of a patient, for example through blood vessels, can be expanded at the deployment location, preferably in a ventricle, and can be operated there.
To remove the pump, it can usually be compressed again and removed through a sluice.
Corresponding compressible pumps are already known in different constructions.
A rotor is, for example, known from WO 03/103745 A2 which has a smaller diameter in a compressed state than in an expanded state and which has an unfoldable rotor blade which unfolds in operation by the fluid counterpressure of the fluid. WO 03/103745 moreover discloses a rotor which has elements which are axially displaceable with respect to one another and whose mutual displacement accompanies the expansion and compression of a cage surrounding the rotor in the manner of a housing.
Rotors are moreover known from the prior art whose impeller blades are unfoldable for operation and have joints or elastic support parts for this purpose. The use of so-called memory alloys such as Nitinol is in particular known which adopt different geometrical shapes in dependence on the environmental temperature and thereby allow a subsequent deformation of the rotor after the introduction into a body.
A fluid pump is known from WO 99/44651 having a compressible rotor which has a compressible coil which is covered by membrane, comprises a memory alloy and is held together axially by an elastic band. The coil can be compressed by radial pressure thereon.
A fluid pump is known from WO 94/05347 having a rotor which carries conveying elements and is fixedly connected to a shaft, with a sleeve moreover being axially displaceably arranged on the shaft by whose displacement a housing surrounding the rotor can be stretched lengthwise and thus radially compressed. A relative movement of the sleeve to the shaft is converted by a lever mechanism into a radial erection of the conveying elements or into a folding down onto the shaft.
A compressible propeller pump with a rotor is known from WO 99/44651 having a helicoidal coil and an elastic band spanned centrally and coaxially therein as well as a membrane spanned between the named elements as an impeller blade.
Experience has shown that complex constructions for such pumps are also difficult to realize and to operate reliably with the desired service lives due to the small construction.